Trapped Key Interlocks Protect Workers at HV Substations

Kirk access interlocks increase safety in switchgear applications, prevent arc flash
North Canton, Ohio (November 21, 2016) – KIRK interlocking products provide safe access to switchgear within HV substations. Trapped key access interlocks and key exchange units restrict physical entry and prevent dangerous operating conditions, ensuring that personnel operate equipment according to the correct sequence of operation.

Kirk Key, HV Substation

Trapped Key Interlocks prevent injury to personnel.

Trapped key interlocks prevent injury to personnel, protect equipment from damage, and assure continuity of electrical supply by initially restricting any unauthorized access. This is particularly important for HV substations located in remote, unmanned sites. Secondly, they ensure that all authorized access is done in a safe manner, requiring that part of a system is isolated and correctly earthed before maintenance can be carried out on that section.

A well-designed interlocking scheme also ensures that the system is operated correctly. This can prevent a number of dangerous scenarios such as: switching two incoming feeds onto a common bus bar, the paralleling of two energy sources, or disconnecting breakers under load. This greatly reduces the risk of fire or arc flash, protecting equipment from damage, preventing injury, and avoiding supply interruption.

For HV substation applications, Kirk recommends its HD Series interlocks. The lock housing, cylinder, and inner workings are manufactured entirely of 316 stainless steel. A robust dowel pin key design resists breakage and prevents duplication. A gasketed flip cover protects the keyways from debris. The HD Series range includes mechanical and electromechanical bolt, access, transfer, and valve interlocks, along with a full range of accessories to form a comprehensive switchgear interlocking scheme for HV substations.


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Kirk Key Interlock Debuts CAD Model Database

Trapped key interlocking models to aid in engineering design projects
North Canton, Ohio (March 16, 2016) – Kirk Key Interlock has launched a new CAD Model database through their website at The new database design allows registered users to download 2D and 3D models of KIRK® products for use by engineers during the design process to check for clearance and mounting options.


The database provides a comprehensive menu of KIRK® products. Registered users can search through the menu, find their specific product needs, view an image of the product chosen, and download the 2D and 3D files.

The link to the CAD Model database can be found on the homepage of the Kirk Key website at under the Quick Links section. Also, with the launch of this database, a newly update website page titled Customer Portal is home to additional product and application downloads, ordering & shipment information, and more.

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Kirk Produces New Application Data Sheet For Emergency Power Tap Box Applications

North Canton, Ohio (October 28, 2016) – Kirk Key Interlock has launched a data sheet explaining how to safely restore power via an emergency generator when a facility’s main power has been lost.

Kirk has launched a data sheet explaining how to safely restore power via an emergency generator when a facility’s main power has been lost

An installed tap box, equipped with KIRK® trapped key interlocks, offers a lower-cost manual transfer alternative to automatic transfer systems, and can reinstate operations with minimal time and dollars lost.

KIRK® key interlocks ensure that a predetermined sequence of operations is performed to prevent crucial safety measures from being omitted while restoring power. KIRK® key interlocks can be installed in the field to existing / previously-installed tap boxes, often without interrupting power. Once installed, the power restoration process can be implemented safely during lost power situations.

The data sheet can be accessed here.

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Kirk Develops Nonlinear Transfer Unit

Offering opportunities for interlocking safety systems within nonlinear sequences
North Canton, Ohio (March 30, 2016) – Kirk Key has developed a trapped key interlock transfer unit to provide safety interlock provisions for trapped key interlocking systems requiring nonlinear sequences. The Type NLTU (Nonlinear Transfer Unit) can be implemented in typical applications such as purging of gases, which requires a nonlinear sequenced process with valve interlocks, to purge gases safely & drive a predetermined non-linear sequence of operations.

Kirk Key, trapped key interlock

Kirk Key has developed a trapped key interlock transfer unit

The Type NLTU incorporates a selector designed and manufactured to customer specified operational requirements. This unit can be manufactured with up to 8 cylinders; 8 non-linear sequenced steps. The unit has a lamacoid affixed to the side of the aluminum housing providing details about the sequenced steps within the operation and the desired action for each step throughout the process.

The Type NLTU is available in the SD Series (Standard Duty – Brass) and HD Series (Heavy Duty – Stainless Steel). As with Kirk’s line of transfer interlocks and panels, the Type NLTU is able to exchange keys across both series enabling the transfer of keys across interlocking systems as required within a process.

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Kirk Key Interlock Safeguards Small Circuit Breakers

Smaller footprint bolt lock offers greater product options for switchgear applications
North Canton, Ohio (April 7, 2015) – Kirk Key has developed a reduced size mechanical bolt interlock for smaller stature breakers. Modelled on the KIRK Standard Duty series Type F, the smaller Type FF ensures that workers follow a pre-determined sequence of operation to safely access electrical switchgear. Manufactured with a brass lock housing and cylinder, the Type FF has a ¾” travel, with a smaller diameter ½” stainless steel lock bolt to better fit in smaller cabinets. The proprietary 7-pin tumbler key design is unique to Kirk and not available commercially, minimizing the risk of circumventing safety sequences with duplicate keys.

Kirk Key Type FF

Kirk Key Type FF reduced size mechanical bolt interlock for smaller circuit breakers.

The Type FF footprint is 2”x1¼” and is generally flat or face mounted with ¼” mounting bolts through the front of the housing. The reduced footprint of the Type FF is approximately 50 percent smaller and nearly 60 percent lighter, allowing for greater clearance around the breaker within the switchgear assembly.

The Type FF, in conjunction with Kirk’s current comprehensive line of Standard Duty bolt, electro-mechanical, access, transfer, and cylinder interlocks, creates a complete trapped key interlock system for switchgear and other process safety applications.

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KIRK Interlocks Debuts New Website

Trapped key interlocking information and products easy to find at  
North Canton, Ohio (March 4, 2015) – KIRK® has launched a redesigned website at The all new site design helps users more easily navigate through trapped key interlocking product and educational information with application specific pages, standards information, and a customer portal.

The new

The site’s new Applications section provides comprehensive information on trapped key interlock use in switchgear, electrostatic precipitators, flow control, ports, perimeter guarding, and other applications. In addition to a general overview, application pages include animations, typical scheme examples, and links to relevant product detail.

The Customer Portal section provides important information on how-to order and a tab for downloads that includes relevant forms, data sheets, and manuals. A secure link to Kirk’s Customer Portal login page provides order status for both open and closed purchase orders, along with order shipping and tracking information.

For quick reference, Kirk provides relevant OSHA, ANSI, IEEE, NEC, and NFPA standards/regulations information for its US customers and MTE regulations for its Brazilian users.

To learn more about Kirk and trapped key interlocking, visit the new

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KIRK Interlocks Safeguard Alternative Maritime Power Connections

Trapped key interlocks increase safety of electrical connections in shore power applications
North Canton, Ohio (January 29, 2015) – KIRK® interlocking products provide safe electrical access during cold ironing, ensuring that ship power cables are properly coupled to shore power junction boxes before energizing. Trapped key access interlocks and key exchange units ensure that users follow a pre-determined sequence of operation when connecting to land based power while in port.

Alternative Marine Power AMP safety

KIRK® interlocking products provide safe electrical access during cold ironing.

In a typical shore power interlocking scheme, a ship’s AMP cable reel is fitted with Kirk’s type DM latch bolts on the shore power plug. The corresponding type DM access interlocks are installed on the junction box’s voltage socket handles inside the quayside vault. A 3-key Kirk transfer block is also installed directly on the front of the junction box. Finally, the upstream breakers powering the junction box are fitted with a Kirk F-lock, keyed to coordinate with the transfer block.

To connect to shore power, the AMP cable is lowered to the wharf. Once both plugs are connected, the two DM latch bolts are inserted into the DM locks. This allows the locks to be engaged, securing the plugs in place and releasing a key for each socket. The two socket keys are then inserted into the transfer block, releasing the third key, used to energize the upstream power. This power key remains trapped in place the entire time the system is energized.

There is no way to circumvent the process; the junction box cannot be energized without first properly connecting the sockets. The socket connection then cannot be broken until the upstream power is shut off, releasing the key required by the transfer block in order to access the two socket release keys.

For cold ironing applications, Kirk recommends its HD Series interlocks. All lock components are manufactured entirely of 316 stainless steel for long service life in corrosive coastal environments. A gasketed flip cover further protects the keyways from salt and debris intrusion.

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KIRK Interlocks Promote Safe Hydrogen Cooled Generator Purging

KIRK Eagle valve and trapped key interlocks guard against operator error
North Canton, Ohio (December 18, 2014) – KIRK® Eagle series valve interlocking products provide process safety control in hydrogen cooled generator purging operations. The company’s Eagle series trapped key valve interlocking systems ensure that users follow a pre-determined sequence of operation for startup and maintenance on generators in power stations, refineries, chemical plants, and other industrial applications. KIRK Eagle series valve interlocks integrate with its mechanical and electromechanical trapped key interlock series to form a comprehensive process safety scheme.


KIRK® Eagle series valve interlocking products provide process safety control in hydrogen cooled generator purging operations.

Purging generator rotating systems with hydrogen reduces drag and windage loss in the system. Improperly introducing air into the generator on startup, without first purging it with carbon dioxide or hydrogen, can create an explosion hazard. By controlling a defined sequence of gas valve operation, proper purging procedures are enforced and hazards minimized.

Interlocking systems are designed to site requirements and are fitted to the gas control valves. The KIRK sequence control unit then regulates the release of the uniquely coded keys required to move safely through the steps of the sequence. The robust oversized keys cannot be duplicated and the sequence cannot be circumvented.

The Eagle series includes integral valve interlocks to fit every type and size of quarter and multi-turn valves, as well as bolt and electro-mechanical interlocks. For long-term use in harsh environments, all Eagle series product offerings are manufactured entirely of 316 stainless steel with keyways protected by a gasketed flip cover.

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Kirk Provides Trapped Key Interlock Delivery and Service to Canadian Electrical Market

Sales team and representative network services electrical switchgear customers across US and Canada; including Federal Pioneer V-Series users
North Canton, OH (November 21, 2014) – Kirk has been manufacturing quality trapped key interlock products and interlocking solutions in the USA since 1932. Over the past 10 years, Kirk has actively expanded its representative base into the Canadian market, partnering with experienced representatives to ensure Canadian customers receive the same high level of service they’ve come to expect from Kirk.

Kirk Reps

Kirk’s Canadian Distributors

Kirk’s representative base extends across Canada. British Columbia, Alberta, Saskatchewan, and Manitoba are served by T&D Products (780-419-7145). Composite Power Group (519-942-8485) serves the Ontario market. Customers in Quebec may contact PTS Electrique (514-457-8886) for service. All representatives and their teams are knowledgeable about Kirk’s products and can aid in determining customer specific needs, products, and schemes.

Kirk has also recently entered into an agreement with Schneider Electric to provide exclusive service for Schneider Electric’s Federal Pioneer V-Series key interlocks. Federal Pioneer customers can contact Kirk directly or work through the Canadian representatives to order replacement keys or equivalent replacement V-Series interlocks.

Kirk key interlocks have been instrumental in protecting personnel and equipment and continue to be an important part of process safety worldwide. Trapped key interlocking is accepted by global standards, safety, and insurance authorities as the most reliable and cost effective method to guard against operator error and hazardous energy discharge.

For more information on Kirk’s products, and assistance with Federal Pioneer products, call a Kirk Canadian representative listed above, or contact Kirk’s technical sales engineers directly at or by phone at 234-209-9301 or 800-438-2442.

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Improve Trapped Key Interlocking Processes with Upgrade to Medium or Heavy Duty Designs

Kirk Key MD and HD Series locks withstand harsh environments and handling for long service life
North Canton, Ohio (September 10, 2014) – Kirk Key’s trapped key interlock systems ensure a pre-determined safety sequence is followed each time hazardous equipment is accessed or operated. Over the past 80 years, its Standard Duty (SD) brass interlocks have earned a reputation for dependable service in a range in applications. To meet the needs of more challenging environments, Kirk now offers Medium Duty (MD) and Heavy Duty (HD) Series options. Constructed to withstand exposure to extremes in temperature, weather, dirt, and corrosive elements, the MD and HD Series deliver long, reliable operation.

Kirk MD HD

Kirk Key MD and HD Series locks withstand harsh environments and handling for long service life.

The construction of both the MD and HD Series interlocks use 316 stainless steel cylinders, keys, bolts, and inner-workings that withstand high temperatures and corrosives in outdoor or harsh environments. The cylinder mechanism has no openings and few moving parts. The shaft driven design prevents dirt and debris from clogging the mechanism. Gasketed keys and dust covers on the interlocks further protect the cylinder from debris.

The HD Series is constructed completely of 316 stainless steel, including the lock body. Ideally suited for chemical applications, passivating electropolishing further protects HD Series interlocks from chemical activity. The MD Series interlocks are constructed with a brass lock body protecting the inner-workings.

The 316 stainless steel dowel pin key design used in the MD and HD series is stronger than typical pin tumbler keys to resist breakage and damage.  The dowel pin design cannot be duplicated or altered to create a master key. Its distinctive shape is less likely to be misplaced or slip through standard floor gratings, minimizing the incidence of lost keys.

MD Series and HD Series ranges include mechanical and electromechanical bolt, access, transfer and valve interlocks, along with a full range of accessories to form a comprehensive interlocking scheme.

To learn more about upgrading an existing system or designing a new interlocking scheme, contact a Kirk technical sales engineer.

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